/*
 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package org.eclipse.imagen.operator;

import java.awt.RenderingHints;
import java.awt.image.RenderedImage;
import java.awt.image.renderable.ParameterBlock;
import org.eclipse.imagen.JAI;
import org.eclipse.imagen.OperationDescriptorImpl;
import org.eclipse.imagen.ParameterBlockJAI;
import org.eclipse.imagen.ROI;
import org.eclipse.imagen.RenderedOp;
import org.eclipse.imagen.registry.RenderedRegistryMode;

/**
 * An <code>OperationDescriptor</code> describing the "Extrema" operation.
 *
 * <p>The Extrema operation scans a specific region of a rendered image and finds the maximum and minimum pixel values
 * for each band within that region of the image. The image data pass through this operation unchanged.
 *
 * <p>The region-wise maximum and minimum pixel values may be obtained as properties. Calling the <code>getProperty
 * </code> method on this operation with "extrema" as the property name retrieves both the region-wise maximum and
 * minimum pixel values. Calling it with "maximum" as the property name retrieves the region-wise maximum pixel value,
 * and with "minimum" as the property name retrieves the region-wise minimum pixel value. The return value for "extrema"
 * has type <code>double[2][#bands]</code>, and those for "maximum" and "minimum" have type <code>double[#bands]</code>.
 *
 * <p>The region of interest (ROI) does not have to be a rectangle. It may be <code>null</code>, in which case the
 * entire image is scanned to find the image-wise maximum and minimum pixel values for each band.
 *
 * <p>The set of pixels scanned may be further reduced by specifying the "xPeriod" and "yPeriod" parameters that
 * represent the sampling rate along each axis. These variables may not be less than 1. However, they may be <code>null
 * </code>, in which case the sampling rate is set to 1; that is, every pixel in the ROI is processed.
 *
 * <p>The <code>Boolean</code> parameter "saveLocations" indicates whether the locations of the extrema will be
 * computed. If <code>TRUE</code>, the locations are computed and stored in the properties "minLocations" and
 * "maxLocations" in the form of lists of run length codes. Each run length code is stored as a three-entry integer
 * array <code>(xStart, yStart,
 * length)</code>. Because the statistics are implemented on the low-resolution image, this <code>length</code> is
 * defined on the image coordinate system of the low-resolution image. Thus, the run length code above means the pixels
 * <code>(xStart, yStart), (xStart + xPeriod, yStart),
 * ..., (xStart + (length - 1) * xPeriod, yStart) </code> of the original image have a value of the maximum or minimum,
 * depending on whether this run exists in the property "maxLocations" or "minLocations". The run length code is
 * row-based, thus the run doesn't wrap on the image boundaries. Runs are not guaranteed to be maximal, e.g. a run that
 * crosses tile boundaries might be broken at the boundary into multiple runs. The order of the runs is not guaranteed.
 *
 * <p>The value objects of the properties "minLocations" and "maxLocations" are arrays of <code>java.util.List</code>.
 * Each array entry contains the minimum/maximum locations of one band. The elements in a list can be accessed using the
 * iterator of the <code>java.util.List</code>. For example, the sample code below demonstrates how to retrieve the
 * minimum locations of the first band:
 *
 * <pre>
 * List minLocations = ((List[])extremaOp.getProperty("minLocations"))[0];
 * Iterator iter = minLocations.iterator();
 * while(iter.hasNext()) {
 *     int[] runLength = (int[])iter.next();
 *     int xStart = runLength[0];
 *          int yStart = runLength[1];
 *          int length = runLength[2];
 *      }
 * </pre>
 *
 * <p>In the implementation of this operator, the proper use of the parameter "saveLocations" also helps to keep the
 * efficiency of the operator in the common case: when only the extremal values are computed.
 *
 * <p>The parameter "maxRuns" is the maximum number of run length codes that the user would like to store. It is defined
 * to reduce memory consumption on very large images. If the parameter "saveLocations" is <code>FALSE</code>, this
 * parameter will be ignored. If this parameter is equal to <code> Integer.MAX_VALUE</code>, all the locations will be
 * saved.
 *
 * <p>
 *
 * <table border=1>
 * <caption>Resource List</caption>
 * <tr><th>Name</th>        <th>Value</th></tr>
 * <tr><td>GlobalName</td>  <td>Extrema</td></tr>
 * <tr><td>LocalName</td>   <td>Extrema</td></tr>
 * <tr><td>Vendor</td>      <td>org.eclipse.imagen.media</td></tr>
 * <tr><td>Description</td> <td>Finds the maximum and minimum pixel value
 *                              in each band of an image.</td></tr>
 * <tr><td>DocURL</td>      <td>http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/operator/ExtremaDescriptor.html</td></tr>
 * <tr><td>Version</td>     <td>1.0</td></tr>
 * <tr><td>arg0Desc</td>    <td>The region of the image to scan.</td></tr>
 * <tr><td>arg1Desc</td>    <td>The horizontal sampling rate,
 *                              may not be less than 1.</td></tr>
 * <tr><td>arg2Desc</td>    <td>The vertical sampling rate,
 *                              may not be less than 1.</td></tr>
 * <tr><td>arg3Desc</td>    <td>Whether to store extrema locations.</td></tr>
 * <tr><td>arg4Desc</td>    <td>Maximum number of run length codes to store.</td></tr>
 * </table>
 *
 * <p>
 *
 * <table border=1>
 * <caption>Parameter List</caption>
 * <tr><th>Name</th>    <th>Class Type</th>
 *                      <th>Default Value</th></tr>
 * <tr><td>roi</td>     <td>org.eclipse.imagen.ROI</td>
 *                      <td>null</td>
 * <tr><td>xPeriod</td> <td>java.lang.Integer</td>
 *                      <td>1</td>
 * <tr><td>yPeriod</td> <td>java.lang.Integer</td>
 *                      <td>1</td>
 * <tr><td>saveLocations</td> <td>java.lang.Boolean</td>
 *                      <td>Boolean.FALSE</td>
 * <tr><td>maxRuns</td> <td>java.lang.Integer</td>
 *                      <td>1</td>
 * </table>
 *
 * @see org.eclipse.imagen.OperationDescriptor
 */
public class ExtremaDescriptor extends OperationDescriptorImpl {

    /**
     * The resource strings that provide the general documentation and specify the parameter list for this operation.
     */
    private static final String[][] resources = {
        {"GlobalName", "Extrema"},
        {"LocalName", "Extrema"},
        {"Vendor", "org.eclipse.imagen.media"},
        {"Description", JaiI18N.getString("ExtremaDescriptor0")},
        {
            "DocURL",
            "http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/operator/ExtremaDescriptor.html"
        },
        {"Version", JaiI18N.getString("DescriptorVersion")},
        {"arg0Desc", JaiI18N.getString("ExtremaDescriptor1")},
        {"arg1Desc", JaiI18N.getString("ExtremaDescriptor2")},
        {"arg2Desc", JaiI18N.getString("ExtremaDescriptor3")},
        {"arg3Desc", JaiI18N.getString("ExtremaDescriptor4")},
        {"arg4Desc", JaiI18N.getString("ExtremaDescriptor5")}
    };

    /** The parameter name list for this operation. */
    private static final String[] paramNames = {"roi", "xPeriod", "yPeriod", "saveLocations", "maxRuns"};

    /** The parameter class list for this operation. */
    private static final Class[] paramClasses = {
        org.eclipse.imagen.ROI.class,
        java.lang.Integer.class,
        java.lang.Integer.class,
        java.lang.Boolean.class,
        java.lang.Integer.class
    };

    /** The parameter default value list for this operation. */
    private static final Object[] paramDefaults = {null, new Integer(1), new Integer(1), Boolean.FALSE, new Integer(1)};

    /** Constructor. */
    public ExtremaDescriptor() {
        super(resources, 1, paramClasses, paramNames, paramDefaults);
    }

    /** Returns the minimum legal value of a specified numeric parameter for this operation. */
    public Number getParamMinValue(int index) {
        if (index == 0 || index == 3) {
            return null;
        } else if (index == 1 || index == 2 || index == 4) {
            return new Integer(1);
        } else {
            throw new ArrayIndexOutOfBoundsException();
        }
    }

    /**
     * Finds the maximum and minimum pixel value in each band of an image.
     *
     * <p>Creates a <code>ParameterBlockJAI</code> from all supplied arguments except <code>hints</code> and invokes
     * {@link JAI#create(String,ParameterBlock,RenderingHints)}.
     *
     * @see JAI
     * @see ParameterBlockJAI
     * @see RenderedOp
     * @param source0 <code>RenderedImage</code> source 0.
     * @param roi The region of the image to scan. May be <code>null</code>.
     * @param xPeriod The horizontal sampling rate, may not be less than 1. May be <code>null</code>.
     * @param yPeriod The vertical sampling rate, may not be less than 1. May be <code>null</code>.
     * @param saveLocations Whether to store extrema locations. May be <code>null</code>.
     * @param maxRuns Maximum number of run length codes to store. May be <code>null</code>.
     * @param hints The <code>RenderingHints</code> to use. May be <code>null</code>.
     * @return The <code>RenderedOp</code> destination.
     * @throws IllegalArgumentException if <code>source0</code> is <code>null</code>.
     */
    public static RenderedOp create(
            RenderedImage source0,
            ROI roi,
            Integer xPeriod,
            Integer yPeriod,
            Boolean saveLocations,
            Integer maxRuns,
            RenderingHints hints) {
        ParameterBlockJAI pb = new ParameterBlockJAI("Extrema", RenderedRegistryMode.MODE_NAME);

        pb.setSource("source0", source0);

        pb.setParameter("roi", roi);
        pb.setParameter("xPeriod", xPeriod);
        pb.setParameter("yPeriod", yPeriod);
        pb.setParameter("saveLocations", saveLocations);
        pb.setParameter("maxRuns", maxRuns);

        return JAI.create("Extrema", pb, hints);
    }
}
